The present invention relates to improvements in a control system for combustion-type appliances as disclosed and claimed in my prior copending application, U.S. Ser. No. 225,729, filed Jan. 15, 1981, now U.S. Pat. No. 4,426,993, with respect to which the present application is a continuation-in-part.
According to my prior copending application, a damper is held closed during non-combustion periods of an appliance by a counterweight, the damper being pivotally suspended by a swingable pivot fixed to an inlet air duct adjacent its lower open end which is blocked by the damper in its closed position. A solenoid is energized to displace the damper toward an open position through a lost-motion connection. The lost-motion connection includes a damper mounted spring biasing the damper to the open position in lagging relation to movement of the solenoid armature through a full power stroke. At the end of its stroke, the armature closes a limit switch to energize a fuel valve during a combustion period while the damper is open to admit a supply of air.